The present invention relates to an improvement in rasp blades used on tire buffing machines to properly precondition tires in preparation for retreading. More particularly, the present invention relates to a tire rasp blade having novel and improved construction of the blade's working edge.
Tire rasp blades have been used for many years in the tire retreading industry. These blades are mounted to the rotating hub of the tire buffing machine and, when engaged with the used tire carcass, they cut, shear or tear small segments of rubber from the tread surface area of the tire. In this way, the tire tread area is "buffed" to achieve an evenly textured surface suitable for retreading. Among the many performance characteristics of such rasp blades, the speed or efficiency of rubber removal is important. However, it is also essential that such blades exhibit good durability--that is, the teeth disposed on the blades should not tear, break or otherwise fail prematurely. It is also desireable that the blades not generate excessive heat during the buffing operation, since the tire surface can be damaged by increased temperatures with the result that an effective retread is not possible.
There are a number of prior art rasp blades that have been developed to meet the performance characteristics noted above. Such rasp blades are disclosed, for example, in U.S. Pat. Nos. 3,879,825; 4,021,899; 4,091,516; and 4,283,819. There still exists a need, however, for a durable tire rasp blade with minimum or no tooth breakage that operates to remove rubber from the tire at a faster rate, while providing excellent surface texture on the buffed tire and maintaining relatively lower buffing temperatures.